/* eslint-disable */
(function() {
    var debug = false;

    var root = this;

    var EXIF = function(obj) {
        if (obj instanceof EXIF) return obj;
        if (!(this instanceof EXIF)) return new EXIF(obj);
        this.EXIFwrapped = obj;
    };

    if (typeof exports !== 'undefined') {
        if (typeof module !== 'undefined' && module.exports) {
            exports = module.exports = EXIF;
        }
        exports.EXIF = EXIF;
    } else {
        root.EXIF = EXIF;
    }

    var ExifTags = (EXIF.Tags = {
        // version tags
        0x9000: 'ExifVersion', // EXIF version
        0xa000: 'FlashpixVersion', // Flashpix format version

        // colorspace tags
        0xa001: 'ColorSpace', // Color space information tag

        // image configuration
        0xa002: 'PixelXDimension', // Valid width of meaningful image
        0xa003: 'PixelYDimension', // Valid height of meaningful image
        0x9101: 'ComponentsConfiguration', // Information about channels
        0x9102: 'CompressedBitsPerPixel', // Compressed bits per pixel

        // user information
        0x927c: 'MakerNote', // Any desired information written by the manufacturer
        0x9286: 'UserComment', // Comments by user

        // related file
        0xa004: 'RelatedSoundFile', // Name of related sound file

        // date and time
        0x9003: 'DateTimeOriginal', // Date and time when the original image was generated
        0x9004: 'DateTimeDigitized', // Date and time when the image was stored digitally
        0x9290: 'SubsecTime', // Fractions of seconds for DateTime
        0x9291: 'SubsecTimeOriginal', // Fractions of seconds for DateTimeOriginal
        0x9292: 'SubsecTimeDigitized', // Fractions of seconds for DateTimeDigitized

        // picture-taking conditions
        0x829a: 'ExposureTime', // Exposure time (in seconds)
        0x829d: 'FNumber', // F number
        0x8822: 'ExposureProgram', // Exposure program
        0x8824: 'SpectralSensitivity', // Spectral sensitivity
        0x8827: 'ISOSpeedRatings', // ISO speed rating
        0x8828: 'OECF', // Optoelectric conversion factor
        0x9201: 'ShutterSpeedValue', // Shutter speed
        0x9202: 'ApertureValue', // Lens aperture
        0x9203: 'BrightnessValue', // Value of brightness
        0x9204: 'ExposureBias', // Exposure bias
        0x9205: 'MaxApertureValue', // Smallest F number of lens
        0x9206: 'SubjectDistance', // Distance to subject in meters
        0x9207: 'MeteringMode', // Metering mode
        0x9208: 'LightSource', // Kind of light source
        0x9209: 'Flash', // Flash status
        0x9214: 'SubjectArea', // Location and area of main subject
        0x920a: 'FocalLength', // Focal length of the lens in mm
        0xa20b: 'FlashEnergy', // Strobe energy in BCPS
        0xa20c: 'SpatialFrequencyResponse', //
        0xa20e: 'FocalPlaneXResolution', // Number of pixels in width direction per FocalPlaneResolutionUnit
        0xa20f: 'FocalPlaneYResolution', // Number of pixels in height direction per FocalPlaneResolutionUnit
        0xa210: 'FocalPlaneResolutionUnit', // Unit for measuring FocalPlaneXResolution and FocalPlaneYResolution
        0xa214: 'SubjectLocation', // Location of subject in image
        0xa215: 'ExposureIndex', // Exposure index selected on camera
        0xa217: 'SensingMethod', // Image sensor type
        0xa300: 'FileSource', // Image source (3 == DSC)
        0xa301: 'SceneType', // Scene type (1 == directly photographed)
        0xa302: 'CFAPattern', // Color filter array geometric pattern
        0xa401: 'CustomRendered', // Special processing
        0xa402: 'ExposureMode', // Exposure mode
        0xa403: 'WhiteBalance', // 1 = auto white balance, 2 = manual
        0xa404: 'DigitalZoomRation', // Digital zoom ratio
        0xa405: 'FocalLengthIn35mmFilm', // Equivalent foacl length assuming 35mm film camera (in mm)
        0xa406: 'SceneCaptureType', // Type of scene
        0xa407: 'GainControl', // Degree of overall image gain adjustment
        0xa408: 'Contrast', // Direction of contrast processing applied by camera
        0xa409: 'Saturation', // Direction of saturation processing applied by camera
        0xa40a: 'Sharpness', // Direction of sharpness processing applied by camera
        0xa40b: 'DeviceSettingDescription', //
        0xa40c: 'SubjectDistanceRange', // Distance to subject

        // other tags
        0xa005: 'InteroperabilityIFDPointer',
        0xa420: 'ImageUniqueID', // Identifier assigned uniquely to each image
    });

    var TiffTags = (EXIF.TiffTags = {
        0x0100: 'ImageWidth',
        0x0101: 'ImageHeight',
        0x8769: 'ExifIFDPointer',
        0x8825: 'GPSInfoIFDPointer',
        0xa005: 'InteroperabilityIFDPointer',
        0x0102: 'BitsPerSample',
        0x0103: 'Compression',
        0x0106: 'PhotometricInterpretation',
        0x0112: 'Orientation',
        0x0115: 'SamplesPerPixel',
        0x011c: 'PlanarConfiguration',
        0x0212: 'YCbCrSubSampling',
        0x0213: 'YCbCrPositioning',
        0x011a: 'XResolution',
        0x011b: 'YResolution',
        0x0128: 'ResolutionUnit',
        0x0111: 'StripOffsets',
        0x0116: 'RowsPerStrip',
        0x0117: 'StripByteCounts',
        0x0201: 'JPEGInterchangeFormat',
        0x0202: 'JPEGInterchangeFormatLength',
        0x012d: 'TransferFunction',
        0x013e: 'WhitePoint',
        0x013f: 'PrimaryChromaticities',
        0x0211: 'YCbCrCoefficients',
        0x0214: 'ReferenceBlackWhite',
        0x0132: 'DateTime',
        0x010e: 'ImageDescription',
        0x010f: 'Make',
        0x0110: 'Model',
        0x0131: 'Software',
        0x013b: 'Artist',
        0x8298: 'Copyright',
    });

    var GPSTags = (EXIF.GPSTags = {
        0x0000: 'GPSVersionID',
        0x0001: 'GPSLatitudeRef',
        0x0002: 'GPSLatitude',
        0x0003: 'GPSLongitudeRef',
        0x0004: 'GPSLongitude',
        0x0005: 'GPSAltitudeRef',
        0x0006: 'GPSAltitude',
        0x0007: 'GPSTimeStamp',
        0x0008: 'GPSSatellites',
        0x0009: 'GPSStatus',
        0x000a: 'GPSMeasureMode',
        0x000b: 'GPSDOP',
        0x000c: 'GPSSpeedRef',
        0x000d: 'GPSSpeed',
        0x000e: 'GPSTrackRef',
        0x000f: 'GPSTrack',
        0x0010: 'GPSImgDirectionRef',
        0x0011: 'GPSImgDirection',
        0x0012: 'GPSMapDatum',
        0x0013: 'GPSDestLatitudeRef',
        0x0014: 'GPSDestLatitude',
        0x0015: 'GPSDestLongitudeRef',
        0x0016: 'GPSDestLongitude',
        0x0017: 'GPSDestBearingRef',
        0x0018: 'GPSDestBearing',
        0x0019: 'GPSDestDistanceRef',
        0x001a: 'GPSDestDistance',
        0x001b: 'GPSProcessingMethod',
        0x001c: 'GPSAreaInformation',
        0x001d: 'GPSDateStamp',
        0x001e: 'GPSDifferential',
    });

    // EXIF 2.3 Spec
    var IFD1Tags = (EXIF.IFD1Tags = {
        0x0100: 'ImageWidth',
        0x0101: 'ImageHeight',
        0x0102: 'BitsPerSample',
        0x0103: 'Compression',
        0x0106: 'PhotometricInterpretation',
        0x0111: 'StripOffsets',
        0x0112: 'Orientation',
        0x0115: 'SamplesPerPixel',
        0x0116: 'RowsPerStrip',
        0x0117: 'StripByteCounts',
        0x011a: 'XResolution',
        0x011b: 'YResolution',
        0x011c: 'PlanarConfiguration',
        0x0128: 'ResolutionUnit',
        0x0201: 'JpegIFOffset', // When image format is JPEG, this value show offset to JPEG data stored.(aka "ThumbnailOffset" or "JPEGInterchangeFormat")
        0x0202: 'JpegIFByteCount', // When image format is JPEG, this value shows data size of JPEG image (aka "ThumbnailLength" or "JPEGInterchangeFormatLength")
        0x0211: 'YCbCrCoefficients',
        0x0212: 'YCbCrSubSampling',
        0x0213: 'YCbCrPositioning',
        0x0214: 'ReferenceBlackWhite',
    });

    var StringValues = (EXIF.StringValues = {
        ExposureProgram: {
            0: 'Not defined',
            1: 'Manual',
            2: 'Normal program',
            3: 'Aperture priority',
            4: 'Shutter priority',
            5: 'Creative program',
            6: 'Action program',
            7: 'Portrait mode',
            8: 'Landscape mode',
        },
        MeteringMode: {
            0: 'Unknown',
            1: 'Average',
            2: 'CenterWeightedAverage',
            3: 'Spot',
            4: 'MultiSpot',
            5: 'Pattern',
            6: 'Partial',
            255: 'Other',
        },
        LightSource: {
            0: 'Unknown',
            1: 'Daylight',
            2: 'Fluorescent',
            3: 'Tungsten (incandescent light)',
            4: 'Flash',
            9: 'Fine weather',
            10: 'Cloudy weather',
            11: 'Shade',
            12: 'Daylight fluorescent (D 5700 - 7100K)',
            13: 'Day white fluorescent (N 4600 - 5400K)',
            14: 'Cool white fluorescent (W 3900 - 4500K)',
            15: 'White fluorescent (WW 3200 - 3700K)',
            17: 'Standard light A',
            18: 'Standard light B',
            19: 'Standard light C',
            20: 'D55',
            21: 'D65',
            22: 'D75',
            23: 'D50',
            24: 'ISO studio tungsten',
            255: 'Other',
        },
        Flash: {
            0x0000: 'Flash did not fire',
            0x0001: 'Flash fired',
            0x0005: 'Strobe return light not detected',
            0x0007: 'Strobe return light detected',
            0x0009: 'Flash fired, compulsory flash mode',
            0x000d: 'Flash fired, compulsory flash mode, return light not detected',
            0x000f: 'Flash fired, compulsory flash mode, return light detected',
            0x0010: 'Flash did not fire, compulsory flash mode',
            0x0018: 'Flash did not fire, auto mode',
            0x0019: 'Flash fired, auto mode',
            0x001d: 'Flash fired, auto mode, return light not detected',
            0x001f: 'Flash fired, auto mode, return light detected',
            0x0020: 'No flash function',
            0x0041: 'Flash fired, red-eye reduction mode',
            0x0045: 'Flash fired, red-eye reduction mode, return light not detected',
            0x0047: 'Flash fired, red-eye reduction mode, return light detected',
            0x0049: 'Flash fired, compulsory flash mode, red-eye reduction mode',
            0x004d: 'Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected',
            0x004f: 'Flash fired, compulsory flash mode, red-eye reduction mode, return light detected',
            0x0059: 'Flash fired, auto mode, red-eye reduction mode',
            0x005d: 'Flash fired, auto mode, return light not detected, red-eye reduction mode',
            0x005f: 'Flash fired, auto mode, return light detected, red-eye reduction mode',
        },
        SensingMethod: {
            1: 'Not defined',
            2: 'One-chip color area sensor',
            3: 'Two-chip color area sensor',
            4: 'Three-chip color area sensor',
            5: 'Color sequential area sensor',
            7: 'Trilinear sensor',
            8: 'Color sequential linear sensor',
        },
        SceneCaptureType: {
            0: 'Standard',
            1: 'Landscape',
            2: 'Portrait',
            3: 'Night scene',
        },
        SceneType: {
            1: 'Directly photographed',
        },
        CustomRendered: {
            0: 'Normal process',
            1: 'Custom process',
        },
        WhiteBalance: {
            0: 'Auto white balance',
            1: 'Manual white balance',
        },
        GainControl: {
            0: 'None',
            1: 'Low gain up',
            2: 'High gain up',
            3: 'Low gain down',
            4: 'High gain down',
        },
        Contrast: {
            0: 'Normal',
            1: 'Soft',
            2: 'Hard',
        },
        Saturation: {
            0: 'Normal',
            1: 'Low saturation',
            2: 'High saturation',
        },
        Sharpness: {
            0: 'Normal',
            1: 'Soft',
            2: 'Hard',
        },
        SubjectDistanceRange: {
            0: 'Unknown',
            1: 'Macro',
            2: 'Close view',
            3: 'Distant view',
        },
        FileSource: {
            3: 'DSC',
        },

        Components: {
            0: '',
            1: 'Y',
            2: 'Cb',
            3: 'Cr',
            4: 'R',
            5: 'G',
            6: 'B',
        },
    });

    function addEvent(element, event, handler) {
        if (element.addEventListener) {
            element.addEventListener(event, handler, false);
        } else if (element.attachEvent) {
            element.attachEvent('on' + event, handler);
        }
    }

    function imageHasData(img) {
        return !!img.exifdata;
    }

    function base64ToArrayBuffer(base64, contentType) {
        contentType = contentType || base64.match(/^data\:([^\;]+)\;base64,/im)[1] || ''; // e.g. 'data:image/jpeg;base64,...' => 'image/jpeg'
        base64 = base64.replace(/^data\:([^\;]+)\;base64,/gim, '');
        var binary = atob(base64);
        var len = binary.length;
        var buffer = new ArrayBuffer(len);
        var view = new Uint8Array(buffer);
        for (var i = 0; i < len; i++) {
            view[i] = binary.charCodeAt(i);
        }
        return buffer;
    }

    function objectURLToBlob(url, callback) {
        var http = new XMLHttpRequest();
        http.open('GET', url, true);
        http.responseType = 'blob';
        http.onload = function(e) {
            if (this.status == 200 || this.status === 0) {
                callback(this.response);
            }
        };
        http.send();
    }

    function getImageData(img, callback) {
        function handleBinaryFile(binFile) {
            var data = findEXIFinJPEG(binFile);
            img.exifdata = data || {};

            // var iptcdata = findIPTCinJPEG(binFile);
            // img.iptcdata = iptcdata || {};
            // fix Uncaught RangeError: Offset is outside the bounds of the DataView
            try {
                img.iptcdata = findIPTCinJPEG(binFile) || {};
            } catch (e) {
                img.iptcdata = {};
            }

            if (EXIF.isXmpEnabled) {
                var xmpdata = findXMPinJPEG(binFile);
                img.xmpdata = xmpdata || {};
            }
            if (callback) {
                callback.call(img);
            }
        }

        if (img.src) {
            if (/^data\:/i.test(img.src)) {
                // Data URI
                var arrayBuffer = base64ToArrayBuffer(img.src);
                handleBinaryFile(arrayBuffer);
            } else if (/^blob\:/i.test(img.src)) {
                // Object URL
                var fileReader = new FileReader();
                fileReader.onload = function(e) {
                    handleBinaryFile(e.target.result);
                };
                objectURLToBlob(img.src, function(blob) {
                    fileReader.readAsArrayBuffer(blob);
                });
            } else {
                var http = new XMLHttpRequest();
                http.onload = function() {
                    if (this.status == 200 || this.status === 0) {
                        handleBinaryFile(http.response);
                    } else {
                        throw 'Could not load image';
                    }
                    http = null;
                };
                http.open('GET', img.src, true);
                http.responseType = 'arraybuffer';
                http.send(null);
            }
        } else if (self.FileReader && (img instanceof self.Blob || img instanceof self.File)) {
            var fileReader = new FileReader();
            fileReader.onload = function(e) {
                if (debug) console.log('Got file of length ' + e.target.result.byteLength);
                handleBinaryFile(e.target.result);
            };

            fileReader.readAsArrayBuffer(img);
        }
    }

    function findEXIFinJPEG(file) {
        var dataView = new DataView(file);

        if (debug) console.log('Got file of length ' + file.byteLength);
        if (dataView.getUint8(0) != 0xff || dataView.getUint8(1) != 0xd8) {
            if (debug) console.log('Not a valid JPEG');
            return false; // not a valid jpeg
        }

        var offset = 2,
            length = file.byteLength,
            marker;

        while (offset < length) {
            if (dataView.getUint8(offset) != 0xff) {
                if (debug)
                    console.log('Not a valid marker at offset ' + offset + ', found: ' + dataView.getUint8(offset));
                return false; // not a valid marker, something is wrong
            }

            marker = dataView.getUint8(offset + 1);
            if (debug) console.log(marker);

            // we could implement handling for other markers here,
            // but we're only looking for 0xFFE1 for EXIF data

            if (marker == 225) {
                if (debug) console.log('Found 0xFFE1 marker');

                return readEXIFData(dataView, offset + 4, dataView.getUint16(offset + 2) - 2);

                // offset += 2 + file.getShortAt(offset+2, true);
            } else {
                offset += 2 + dataView.getUint16(offset + 2);
            }
        }
    }

    function findIPTCinJPEG(file) {
        var dataView = new DataView(file);

        if (debug) console.log('Got file of length ' + file.byteLength);
        if (dataView.getUint8(0) != 0xff || dataView.getUint8(1) != 0xd8) {
            if (debug) console.log('Not a valid JPEG');
            return false; // not a valid jpeg
        }

        var offset = 2,
            length = file.byteLength;

        var isFieldSegmentStart = function(dataView, offset) {
            return (
                dataView.getUint8(offset) === 0x38 &&
                dataView.getUint8(offset + 1) === 0x42 &&
                dataView.getUint8(offset + 2) === 0x49 &&
                dataView.getUint8(offset + 3) === 0x4d &&
                dataView.getUint8(offset + 4) === 0x04 &&
                dataView.getUint8(offset + 5) === 0x04
            );
        };

        while (offset < length) {
            if (isFieldSegmentStart(dataView, offset)) {
                // Get the length of the name header (which is padded to an even number of bytes)
                var nameHeaderLength = dataView.getUint8(offset + 7);
                if (nameHeaderLength % 2 !== 0) nameHeaderLength += 1;
                // Check for pre photoshop 6 format
                if (nameHeaderLength === 0) {
                    // Always 4
                    nameHeaderLength = 4;
                }

                var startOffset = offset + 8 + nameHeaderLength;
                var sectionLength = dataView.getUint16(offset + 6 + nameHeaderLength);

                return readIPTCData(file, startOffset, sectionLength);

                break;
            }

            // Not the marker, continue searching
            offset++;
        }
    }
    var IptcFieldMap = {
        0x78: 'caption',
        0x6e: 'credit',
        0x19: 'keywords',
        0x37: 'dateCreated',
        0x50: 'byline',
        0x55: 'bylineTitle',
        0x7a: 'captionWriter',
        0x69: 'headline',
        0x74: 'copyright',
        0x0f: 'category',
    };
    function readIPTCData(file, startOffset, sectionLength) {
        var dataView = new DataView(file);
        var data = {};
        var fieldValue, fieldName, dataSize, segmentType, segmentSize;
        var segmentStartPos = startOffset;
        while (segmentStartPos < startOffset + sectionLength) {
            if (dataView.getUint8(segmentStartPos) === 0x1c && dataView.getUint8(segmentStartPos + 1) === 0x02) {
                segmentType = dataView.getUint8(segmentStartPos + 2);
                if (segmentType in IptcFieldMap) {
                    dataSize = dataView.getInt16(segmentStartPos + 3);
                    segmentSize = dataSize + 5;
                    fieldName = IptcFieldMap[segmentType];
                    fieldValue = getStringFromDB(dataView, segmentStartPos + 5, dataSize);
                    // Check if we already stored a value with this name
                    if (data.hasOwnProperty(fieldName)) {
                        // Value already stored with this name, create multivalue field
                        if (data[fieldName] instanceof Array) {
                            data[fieldName].push(fieldValue);
                        } else {
                            data[fieldName] = [data[fieldName], fieldValue];
                        }
                    } else {
                        data[fieldName] = fieldValue;
                    }
                }
            }
            segmentStartPos++;
        }
        return data;
    }

    function readTags(file, tiffStart, dirStart, strings, bigEnd) {
        var entries = file.getUint16(dirStart, !bigEnd),
            tags = {},
            entryOffset,
            tag,
            i;

        for (i = 0; i < entries; i++) {
            entryOffset = dirStart + i * 12 + 2;
            tag = strings[file.getUint16(entryOffset, !bigEnd)];
            if (!tag && debug) console.log('Unknown tag: ' + file.getUint16(entryOffset, !bigEnd));
            tags[tag] = readTagValue(file, entryOffset, tiffStart, dirStart, bigEnd);
        }
        return tags;
    }

    function readTagValue(file, entryOffset, tiffStart, dirStart, bigEnd) {
        var type = file.getUint16(entryOffset + 2, !bigEnd),
            numValues = file.getUint32(entryOffset + 4, !bigEnd),
            valueOffset = file.getUint32(entryOffset + 8, !bigEnd) + tiffStart,
            offset,
            vals,
            val,
            n,
            numerator,
            denominator;

        switch (type) {
            case 1: // byte, 8-bit unsigned int
            case 7: // undefined, 8-bit byte, value depending on field
                if (numValues == 1) {
                    return file.getUint8(entryOffset + 8, !bigEnd);
                } else {
                    offset = numValues > 4 ? valueOffset : entryOffset + 8;
                    vals = [];
                    for (n = 0; n < numValues; n++) {
                        vals[n] = file.getUint8(offset + n);
                    }
                    return vals;
                }

            case 2: // ascii, 8-bit byte
                offset = numValues > 4 ? valueOffset : entryOffset + 8;
                return getStringFromDB(file, offset, numValues - 1);

            case 3: // short, 16 bit int
                if (numValues == 1) {
                    return file.getUint16(entryOffset + 8, !bigEnd);
                } else {
                    offset = numValues > 2 ? valueOffset : entryOffset + 8;
                    vals = [];
                    for (n = 0; n < numValues; n++) {
                        vals[n] = file.getUint16(offset + 2 * n, !bigEnd);
                    }
                    return vals;
                }

            case 4: // long, 32 bit int
                if (numValues == 1) {
                    return file.getUint32(entryOffset + 8, !bigEnd);
                } else {
                    vals = [];
                    for (n = 0; n < numValues; n++) {
                        vals[n] = file.getUint32(valueOffset + 4 * n, !bigEnd);
                    }
                    return vals;
                }

            case 5: // rational = two long values, first is numerator, second is denominator
                if (numValues == 1) {
                    numerator = file.getUint32(valueOffset, !bigEnd);
                    denominator = file.getUint32(valueOffset + 4, !bigEnd);
                    val = new Number(numerator / denominator);
                    val.numerator = numerator;
                    val.denominator = denominator;
                    return val;
                } else {
                    vals = [];
                    for (n = 0; n < numValues; n++) {
                        numerator = file.getUint32(valueOffset + 8 * n, !bigEnd);
                        denominator = file.getUint32(valueOffset + 4 + 8 * n, !bigEnd);
                        vals[n] = new Number(numerator / denominator);
                        vals[n].numerator = numerator;
                        vals[n].denominator = denominator;
                    }
                    return vals;
                }

            case 9: // slong, 32 bit signed int
                if (numValues == 1) {
                    return file.getInt32(entryOffset + 8, !bigEnd);
                } else {
                    vals = [];
                    for (n = 0; n < numValues; n++) {
                        vals[n] = file.getInt32(valueOffset + 4 * n, !bigEnd);
                    }
                    return vals;
                }

            case 10: // signed rational, two slongs, first is numerator, second is denominator
                if (numValues == 1) {
                    return file.getInt32(valueOffset, !bigEnd) / file.getInt32(valueOffset + 4, !bigEnd);
                } else {
                    vals = [];
                    for (n = 0; n < numValues; n++) {
                        vals[n] =
                            file.getInt32(valueOffset + 8 * n, !bigEnd) /
                            file.getInt32(valueOffset + 4 + 8 * n, !bigEnd);
                    }
                    return vals;
                }
        }
    }

    /**
     * Given an IFD (Image File Directory) start offset
     * returns an offset to next IFD or 0 if it's the last IFD.
     */
    function getNextIFDOffset(dataView, dirStart, bigEnd) {
        //the first 2bytes means the number of directory entries contains in this IFD
        var entries = dataView.getUint16(dirStart, !bigEnd);

        // After last directory entry, there is a 4bytes of data,
        // it means an offset to next IFD.
        // If its value is '0x00000000', it means this is the last IFD and there is no linked IFD.

        return dataView.getUint32(dirStart + 2 + entries * 12, !bigEnd); // each entry is 12 bytes long
    }

    function readThumbnailImage(dataView, tiffStart, firstIFDOffset, bigEnd) {
        // get the IFD1 offset
        var IFD1OffsetPointer = getNextIFDOffset(dataView, tiffStart + firstIFDOffset, bigEnd);

        if (!IFD1OffsetPointer) {
            // console.log('******** IFD1Offset is empty, image thumb not found ********');
            return {};
        } else if (IFD1OffsetPointer > dataView.byteLength) {
            // this should not happen
            // console.log('******** IFD1Offset is outside the bounds of the DataView ********');
            return {};
        }
        // console.log('*******  thumbnail IFD offset (IFD1) is: %s', IFD1OffsetPointer);

        var thumbTags = readTags(dataView, tiffStart, tiffStart + IFD1OffsetPointer, IFD1Tags, bigEnd);

        // EXIF 2.3 specification for JPEG format thumbnail

        // If the value of Compression(0x0103) Tag in IFD1 is '6', thumbnail image format is JPEG.
        // Most of Exif image uses JPEG format for thumbnail. In that case, you can get offset of thumbnail
        // by JpegIFOffset(0x0201) Tag in IFD1, size of thumbnail by JpegIFByteCount(0x0202) Tag.
        // Data format is ordinary JPEG format, starts from 0xFFD8 and ends by 0xFFD9. It seems that
        // JPEG format and 160x120pixels of size are recommended thumbnail format for Exif2.1 or later.

        if (thumbTags['Compression']) {
            // console.log('Thumbnail image found!');

            switch (thumbTags['Compression']) {
                case 6:
                    // console.log('Thumbnail image format is JPEG');
                    if (thumbTags.JpegIFOffset && thumbTags.JpegIFByteCount) {
                        // extract the thumbnail
                        var tOffset = tiffStart + thumbTags.JpegIFOffset;
                        var tLength = thumbTags.JpegIFByteCount;
                        thumbTags['blob'] = new Blob([new Uint8Array(dataView.buffer, tOffset, tLength)], {
                            type: 'image/jpeg',
                        });
                    }
                    break;

                case 1:
                    console.log('Thumbnail image format is TIFF, which is not implemented.');
                    break;
                default:
                    console.log("Unknown thumbnail image format '%s'", thumbTags['Compression']);
            }
        } else if (thumbTags['PhotometricInterpretation'] == 2) {
            console.log('Thumbnail image format is RGB, which is not implemented.');
        }
        return thumbTags;
    }

    function getStringFromDB(buffer, start, length) {
        var outstr = '';
        for (n = start; n < start + length; n++) {
            outstr += String.fromCharCode(buffer.getUint8(n));
        }
        return outstr;
    }

    function readEXIFData(file, start) {
        if (getStringFromDB(file, start, 4) != 'Exif') {
            if (debug) console.log('Not valid EXIF data! ' + getStringFromDB(file, start, 4));
            return false;
        }

        var bigEnd,
            tags,
            tag,
            exifData,
            gpsData,
            tiffOffset = start + 6;

        // test for TIFF validity and endianness
        if (file.getUint16(tiffOffset) == 0x4949) {
            bigEnd = false;
        } else if (file.getUint16(tiffOffset) == 0x4d4d) {
            bigEnd = true;
        } else {
            if (debug) console.log('Not valid TIFF data! (no 0x4949 or 0x4D4D)');
            return false;
        }

        if (file.getUint16(tiffOffset + 2, !bigEnd) != 0x002a) {
            if (debug) console.log('Not valid TIFF data! (no 0x002A)');
            return false;
        }

        var firstIFDOffset = file.getUint32(tiffOffset + 4, !bigEnd);

        if (firstIFDOffset < 0x00000008) {
            if (debug)
                console.log('Not valid TIFF data! (First offset less than 8)', file.getUint32(tiffOffset + 4, !bigEnd));
            return false;
        }

        tags = readTags(file, tiffOffset, tiffOffset + firstIFDOffset, TiffTags, bigEnd);

        if (tags.ExifIFDPointer) {
            exifData = readTags(file, tiffOffset, tiffOffset + tags.ExifIFDPointer, ExifTags, bigEnd);
            for (tag in exifData) {
                switch (tag) {
                    case 'LightSource':
                    case 'Flash':
                    case 'MeteringMode':
                    case 'ExposureProgram':
                    case 'SensingMethod':
                    case 'SceneCaptureType':
                    case 'SceneType':
                    case 'CustomRendered':
                    case 'WhiteBalance':
                    case 'GainControl':
                    case 'Contrast':
                    case 'Saturation':
                    case 'Sharpness':
                    case 'SubjectDistanceRange':
                    case 'FileSource':
                        exifData[tag] = StringValues[tag][exifData[tag]];
                        break;

                    case 'ExifVersion':
                    case 'FlashpixVersion':
                        exifData[tag] = String.fromCharCode(
                            exifData[tag][0],
                            exifData[tag][1],
                            exifData[tag][2],
                            exifData[tag][3]
                        );
                        break;

                    case 'ComponentsConfiguration':
                        exifData[tag] =
                            StringValues.Components[exifData[tag][0]] +
                            StringValues.Components[exifData[tag][1]] +
                            StringValues.Components[exifData[tag][2]] +
                            StringValues.Components[exifData[tag][3]];
                        break;
                }
                tags[tag] = exifData[tag];
            }
        }
        // 鲁延涛注释
        if (false && tags.GPSInfoIFDPointer) {
            gpsData = readTags(file, tiffOffset, tiffOffset + tags.GPSInfoIFDPointer, GPSTags, bigEnd);
            for (tag in gpsData) {
                switch (tag) {
                    case 'GPSVersionID':
                        gpsData[tag] =
                            gpsData[tag][0] + '.' + gpsData[tag][1] + '.' + gpsData[tag][2] + '.' + gpsData[tag][3];
                        break;
                }
                tags[tag] = gpsData[tag];
            }
        }

        // extract thumbnail
        // luyantao注释
        // tags['thumbnail'] = readThumbnailImage(file, tiffOffset, firstIFDOffset, bigEnd);

        return tags;
    }

    function findXMPinJPEG(file) {
        if (!('DOMParser' in self)) {
            // console.warn('XML parsing not supported without DOMParser');
            return;
        }
        var dataView = new DataView(file);

        if (debug) console.log('Got file of length ' + file.byteLength);
        if (dataView.getUint8(0) != 0xff || dataView.getUint8(1) != 0xd8) {
            if (debug) console.log('Not a valid JPEG');
            return false; // not a valid jpeg
        }

        var offset = 2,
            length = file.byteLength,
            dom = new DOMParser();

        while (offset < length - 4) {
            if (getStringFromDB(dataView, offset, 4) == 'http') {
                var startOffset = offset - 1;
                var sectionLength = dataView.getUint16(offset - 2) - 1;
                var xmpString = getStringFromDB(dataView, startOffset, sectionLength);
                var xmpEndIndex = xmpString.indexOf('xmpmeta>') + 8;
                xmpString = xmpString.substring(xmpString.indexOf('<x:xmpmeta'), xmpEndIndex);

                var indexOfXmp = xmpString.indexOf('x:xmpmeta') + 10;
                //Many custom written programs embed xmp/xml without any namespace. Following are some of them.
                //Without these namespaces, XML is thought to be invalid by parsers
                xmpString =
                    xmpString.slice(0, indexOfXmp) +
                    'xmlns:Iptc4xmpCore="http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/" ' +
                    'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ' +
                    'xmlns:tiff="http://ns.adobe.com/tiff/1.0/" ' +
                    'xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus" ' +
                    'xmlns:ext="http://www.gettyimages.com/xsltExtension/1.0" ' +
                    'xmlns:exif="http://ns.adobe.com/exif/1.0/" ' +
                    'xmlns:stEvt="http://ns.adobe.com/xap/1.0/sType/ResourceEvent#" ' +
                    'xmlns:stRef="http://ns.adobe.com/xap/1.0/sType/ResourceRef#" ' +
                    'xmlns:crs="http://ns.adobe.com/camera-raw-settings/1.0/" ' +
                    'xmlns:xapGImg="http://ns.adobe.com/xap/1.0/g/img/" ' +
                    'xmlns:Iptc4xmpExt="http://iptc.org/std/Iptc4xmpExt/2008-02-29/" ' +
                    xmpString.slice(indexOfXmp);

                var domDocument = dom.parseFromString(xmpString, 'text/xml');
                return xml2Object(domDocument);
            } else {
                offset++;
            }
        }
    }

    function xml2json(xml) {
        var json = {};

        if (xml.nodeType == 1) {
            // element node
            if (xml.attributes.length > 0) {
                json['@attributes'] = {};
                for (var j = 0; j < xml.attributes.length; j++) {
                    var attribute = xml.attributes.item(j);
                    json['@attributes'][attribute.nodeName] = attribute.nodeValue;
                }
            }
        } else if (xml.nodeType == 3) {
            // text node
            return xml.nodeValue;
        }

        // deal with children
        if (xml.hasChildNodes()) {
            for (var i = 0; i < xml.childNodes.length; i++) {
                var child = xml.childNodes.item(i);
                var nodeName = child.nodeName;
                if (json[nodeName] == null) {
                    json[nodeName] = xml2json(child);
                } else {
                    if (json[nodeName].push == null) {
                        var old = json[nodeName];
                        json[nodeName] = [];
                        json[nodeName].push(old);
                    }
                    json[nodeName].push(xml2json(child));
                }
            }
        }

        return json;
    }

    function xml2Object(xml) {
        try {
            var obj = {};
            if (xml.children.length > 0) {
                for (var i = 0; i < xml.children.length; i++) {
                    var item = xml.children.item(i);
                    var attributes = item.attributes;
                    for (var idx in attributes) {
                        var itemAtt = attributes[idx];
                        var dataKey = itemAtt.nodeName;
                        var dataValue = itemAtt.nodeValue;

                        if (dataKey !== undefined) {
                            obj[dataKey] = dataValue;
                        }
                    }
                    var nodeName = item.nodeName;

                    if (typeof obj[nodeName] == 'undefined') {
                        obj[nodeName] = xml2json(item);
                    } else {
                        if (typeof obj[nodeName].push == 'undefined') {
                            var old = obj[nodeName];

                            obj[nodeName] = [];
                            obj[nodeName].push(old);
                        }
                        obj[nodeName].push(xml2json(item));
                    }
                }
            } else {
                obj = xml.textContent;
            }
            return obj;
        } catch (e) {
            console.log(e.message);
        }
    }

    EXIF.enableXmp = function() {
        EXIF.isXmpEnabled = true;
    };

    EXIF.disableXmp = function() {
        EXIF.isXmpEnabled = false;
    };

    EXIF.getData = function(img, callback) {
        if (
            ((self.Image && img instanceof self.Image) ||
                (self.HTMLImageElement && img instanceof self.HTMLImageElement)) &&
            !img.complete
        )
            return false;

        if (!imageHasData(img)) {
            getImageData(img, callback);
        } else {
            if (callback) {
                callback.call(img);
            }
        }
        return true;
    };

    EXIF.getTag = function(img, tag) {
        if (!imageHasData(img)) return;
        return img.exifdata[tag];
    };

    EXIF.getIptcTag = function(img, tag) {
        if (!imageHasData(img)) return;
        return img.iptcdata[tag];
    };

    EXIF.getAllTags = function(img) {
        if (!imageHasData(img)) return {};
        var a,
            data = img.exifdata,
            tags = {};
        for (a in data) {
            if (data.hasOwnProperty(a)) {
                tags[a] = data[a];
            }
        }
        return tags;
    };

    EXIF.getAllIptcTags = function(img) {
        if (!imageHasData(img)) return {};
        var a,
            data = img.iptcdata,
            tags = {};
        for (a in data) {
            if (data.hasOwnProperty(a)) {
                tags[a] = data[a];
            }
        }
        return tags;
    };

    EXIF.pretty = function(img) {
        if (!imageHasData(img)) return '';
        var a,
            data = img.exifdata,
            strPretty = '';
        for (a in data) {
            if (data.hasOwnProperty(a)) {
                if (typeof data[a] == 'object') {
                    if (data[a] instanceof Number) {
                        strPretty +=
                            a + ' : ' + data[a] + ' [' + data[a].numerator + '/' + data[a].denominator + ']\r\n';
                    } else {
                        strPretty += a + ' : [' + data[a].length + ' values]\r\n';
                    }
                } else {
                    strPretty += a + ' : ' + data[a] + '\r\n';
                }
            }
        }
        return strPretty;
    };

    EXIF.readFromBinaryFile = function(file) {
        return findEXIFinJPEG(file);
    };

    if (typeof define === 'function' && define.amd) {
        define('exif-js', [], function() {
            return EXIF;
        });
    }
}.call(this));
